Session for SDN Event. In this session Mark Taling and I explain how we used NServiceBus and SignalR to publish real time events from a production monitor. After a short intro to NServiceBus and SignalR, we dive into some techniques for combining the two: 1) SignalR for relaying events from the back end to a wide range of clients 2) Using SignalR as a transport for NServiceBus 3) Using NServiceBus as a backplane for scaling out SignalR

1. Real Time
Event Feeds
with
NServiceBus
and
@roycornelissen
SignalR #SIGNALR
#NSERVICEBUS
@marktaling
#SDE

2. Combining
Introduction NServiceBus SignalR
the two
Demos

4. Showcase: real time monitor
production
gateway
monitor

5. Showcase: real time monitor
monitor service gateway
Plugins
SendAvailablePlugins
PluginAvailable (3x)
[connect]
Powered By

8. A service bus
is an
architectural style
for integration
To simplify communication between
services in a distributed system
NServiceBus

9. Loose coupling
Share contract and schema,
not class
Temporal decoupling through
queued messaging

10. Where is
“the bus”?
Like Ethernet, it’s
everywhere!

11. A .NET framework to help implement SOA
with the Service Bus architectural style
Abstracts away transport, threading,
queues, transactions
Focuses on implementing business logic
Highly pluggable

12. developers!
developers!
developers!
Very developer
focused

16. http has a pull model

17. The push concept
The server takes the
initiative to send data
to the client

18. Push protocols
irc smtp websocket server sent
events

19. Two way, persistent connection, initiated
by client
W3C draft, worked on by IETF
Support (partial) in some browsers

20. Server side events
“Pub/Sub” like protocol over http
Also still a W3C draft
One-way, client needs extra channel for send
Proxies need to know about
content-type:text/event-stream

21. But I want it now!
Veruca Salt
Willy Wonka & The Chocolate Factory, 1971

22. Other options
long polling
client 1
Got msg? “message” Got msg? “message”
server
POST “message” POST “message”
client 2
forever frame
<iframe src=“/forever”>
client 1 <script> <script>
GET /forever display(“message”); display(“message”);
</script> </script>
server
POST “message” POST “message”
client 2

23. SignalR to the rescue

24. SignalR will abstract away the
actual protocol used, and adds
a couple of layers on top to
make things even easier
SignalR’s layers of abstraction

25. hub
persistent connection
SignalR 1.0 protocols
web sockets server events long polling forever frame
• Unified programming model
• Deals with connectivity issues (connection slow, reconnect, disconnects)
• Available for multiple types of clients
• Messaging bus
• Utilizes Json.NET for serialization

26. hubs

27. Client/server boundaries fade
Hubs let you provide a semantic API between client and server
SignalR creates a proxy between the two parties
client (javascript) server
var chat = $.connection.chatHub; class ChatHub: Hub
… {
chat.server.message(“hi!”); proxy public void message(string text)
… {
chat.client.notify = function(text) Clients.All.notify(text);
{ }
// do something with text }
} dynamic

29. SignalR options
clients
Windows
JavaScript .NET Silverlight WinRT iOS Android
Phone
Service
ASP.NET OWIN Custom SQL Redis
Bus
hosts backplanes

31. Gateway
input
queue
Gateway
Monitor Service
MonitorHub: Hub
GlobalHost
.ConnectionManager NServiceBus
.GetHubContext<MonitorHub>();.
input
queue
MessageForwarder:
IHandleMessages<T>
IIS AppFabric

33. Transport
Gateway
Monitor Service
NServiceBus MonitorHub: Hub
NServiceBus
SignalR
IIS AppFabric

35. SignalR transport
The Good
Transparent: no
notion of SignalR
NServiceBus in
the client

36. SignalR transport
The Bad
No guaranteed
delivery
No transaction
support

37. Scaling out SignalR via backplanes
?
B
NServiceBus

38. An NServiceBus backplane
input
queue
Backplane Service
SignalR
MessageDispatcher:
IHandleMessages<DistributeMessage>
NServiceBusMessageBus: Bus.Send<DistributeMessage>()
ScaleoutMessageBus
NServiceBus
OnReceived(…);.
input Bus.Publish<MessagesAvailable>()
queue
Receiver:
IHandleMessages<MessagesAvailable>
IIS AppFabric

40. SignalR backplane
Considerations
Reliability offered
by NServiceBus
What about
scalability of the
backplane service
itself?

41. Links
www.nuget.org
www.nservicebus.com
www.github.com/nservicebus
www.udidahan.com
www.github.com/signalr
www.github.com/gshackles/signalr

42. @roycornelissen
royc@infosupport.com
roycornelissen.wordpress.com
@marktaling
markt@infosupport.com
thanks!